1. Field of the Invention
The present invention relates generally to a ruggedized fiber optic connector assembly, also referred to as a fiber optic “plug.” More specifically, the present invention relates to a ruggedized fiber optic connector assembly that incorporates a retention body, or glue body, that is configured to both retain a fiber optic cable, preferably having one or more strength members, and engage a fiber optic receptacle or, alternatively, another fiber optic connector assembly.
2. Technical Background of the Invention
Optical fiber is increasingly being used for a variety of broadband applications, including voice, video, and data transmission. As a result, fiber optic communications networks include a number of interconnection points at which multiple optical fibers are interconnected. Fiber optic communications networks also include a number of connection terminals, examples of which include, but are not limited to, network access point (NAP) enclosures, aerial closures, below grade closures, pedestals, optical network terminals (ONTs), network interface devices (NIDs), and multi-port devices. In certain instances, the connection terminals include connector ports, typically opening through an external wall of the connection terminals, that are used to establish optical connections between optical fibers that are terminated from a distribution cable and respective optical fibers of one or more pre-connectorized drop cables, extended distribution cables, tether cables, or branch cables, collectively referred to as “drop cables.” The connection terminals are used to readily extend fiber optic communications services to a subscriber. In this regard, fiber optic communications networks are being developed that deliver “fiber-to-the-curb” (FTTC), “fiber-to-the-business” (FTTB), “fiber-to-the-home” (FTTH), and “fiber-to-the-premises” (FTTP), generically referred to as “FTTx.”
A conventional connector port opening through an external wall of a connection terminal typically includes a receptacle that is configured to receive a connectorized optical fiber on the inside of the terminal, and a connectorized drop cable on the outside of the terminal. One of the mating ferrules is mounted on the end of an optical fiber that is optically interconnected to at least one optical fiber of the distribution cable within the connection terminal. The other mating ferrule is mounted on the end of an optical fiber of a drop cable that is inserted into the receptacle from the outside of the connection terminal. An alignment sleeve of the receptacle typically assists in the alignment of the ferrules, and ferrule guide pins or other alignment means may further assist in the precise alignment of multifiber ferrules.
In particular, a plug mounted on the end of the drop cable engages one side of a corresponding receptacle. Typically, the plug includes a substantially cylindrical plug body, and a fiber optic connector including a plug ferrule disposed within the plug body. The end of the plug body is open, or is provided with one or more openings, such that the ferrule is accessible within the plug body, for example to be cleaned. The ferrule is mounted on the end of one or more optical fibers of the drop cable such that mating the plug with the receptacle aligns the optical fibers of the drop cable with the respective optical fibers terminated from the distribution cable within the connection terminal. In the process of mating the plug with the receptacle, the ferrule is inserted into one end of the alignment sleeve housed within the receptacle. As a result of the construction of a conventional plug, the alignment sleeve is minimally received within the open end of the plug body as the ferrule is inserted into the alignment sleeve. As an alternative to the above, the plug mounted on the end of the drop cable engages a plug mounted on the end of another drop cable or another receptacle not associated with a connection terminal, such as that associated with a business, home, premises, etc.
Several different types of conventional connectors have been developed, examples of which include, but are not limited to, SC, ST, LC, MTP, MT-RJ, and SC-DC. The size and shape of the ferrule of each of these connectors is somewhat different. Correspondingly, the size and shape of the plug body and alignment sleeve are somewhat different. As a result, in conventional practice, different plugs and receptacles are used in conjunction with different ferrules. In this regard, the receptacles generally define different sized internal cavities and features corresponding to different sized alignment sleeves and plug bodies, and, in turn, different ferrules disposed within the plug bodies and alignment sleeves.
Referring to prior art FIG. 1, a conventional connector 10 includes a plug housing 12 in which a crimp body 14 including two halves 14a,14b and a crimp band 16 are axially disposed during assembly. A heat shrink 18 is also utilized, as described in greater detail below. Collectively, the crimp body 14 and crimp band 16 retain both a drop cable 20 and a connector sub-assembly 22 (i.e., a pre-assembled ferrule holder module), the connector sub-assembly 22 holding a ferrule 24. Specifically, a shaft 25 of the connector sub-assembly 22 is secured between the two halves 14a,14b of the crimp body 14. As a result, an optical fiber of the drop cable 20 and the ferrule 24 are optically connected. The heat shrink 18 is disposed about an end portion of the plug housing 12 and an end portion of the drop cable 20, thereby providing some retention force and stress relief, and a flexible environmental seal. As illustrated, the drop cable 20 is a single-fiber drop cable and the ferrule 24 is a single-termination ferrule, although other types of drop cables, optical fibers, and ferrules could be used with other types of connectors. This inner assembly is partially housed within a coupling nut 26 that is externally threaded such that the connector 10 is configured to engage the internal threading of an alignment sleeve of a receptacle (not shown), thereby aligning and optically mating the ferrule 24 of the connector 10 and a ferrule of the receptacle. As described above, guide pins or other alignment means may assist in more precise alignment of multi-fiber ferrules. For example, the end of the plug housing 12 and the alignment sleeve and/or receptacle may be keyed. The connector 10 also includes one or more silicone O-rings 28 that environmentally seal the connector 10 and receptacle, when joined, and a boot 30 that further relieves stress in the drop cable 20. Finally, the connector 10 incorporates one or more dust caps 32,34 that are used to selectively protect the ferrule 24 and the exposed end of the plug housing 12. Preferably, the larger of the dust caps 34, also referred to as the “pulling cap,” is internally threaded such that it is configured to engage the external threading of the coupling nut 26. Finally, the pulling cap 34 is secured to the boot 20 via a plastic lanyard 36 or other retention means, such that the pulling cap 34 is not easily lost. The connector 10 provides a hardened connector for outside plant deployment and incorporates an integral pulling eye 38 designed for pulling tension.
As of yet, however, there is an unresolved need for an alternative (or additional) retention method for dealing with otherwise incompatible drop cable strength members, such as glass-reinforced plastic (GRP) strength members and the like. The handling and mating of the two halves 14a,14b of the crimp body 14 described above often applies excessive stress and jeopardizes the optical fiber (which typically has a diameter of about 250 μm) during termination. Further, this crimp design alone is typically not strong enough to meet pulling tension requirements, necessitating the use of an adhesive. This adhesive rigidly fixes the connector sub-assembly, eliminating the ability to compensate for radial offset due to manufacturing tolerances. This radial offset can be compensated for by “floating” the adapter, however, in a plug-to-plug arrangement, there is no such floating element. Thus, manufacturing tolerances become much more stringent. Still further, this crimp design, incorporating the heat shrink 18, relies on a hard stop of the plug housing 12 against the coupling nut 26 and, ultimately, the heat shrink 18 itself to keep the drop cable 20 and the connector sub-assembly 22 in the same position during process and use. In a high temperature environment, and due to improper fixturing during the application of the heat shrink 18, the plug housing 12 is allowed to move axially and piston in and out of position. As of yet, there is also an unresolved need for an alternative retention method that does not allow multiple ways (i.e., two 180-degree opposing ways) to assemble the connector components, thereby requiring fixturing and verification by an operator in order to make sure that the connector sub-assembly 22 is oriented properly. On occasion, this requires the cutting off of a good connector as the orientation of the endface angle is incompatible, resulting in wasteful scrap.